What the Anesthesiologist Should Know before the Operative Procedure

Choledochal cysts (CCs) are rare medical conditions due to aberrant dilatation of the common bile duct that may cause obstruction in biliary flow. Incidence in western population is 1 in 100,000 to 150,000 live births, although the incidence is as high as 1 in 13,500 in the United States and 1 in 15,000 births in Australia. The rates are remarkably higher in Asian populations, with an incidence of 1 in 1,000 and about two-thirds of cases occur in Japan. There is also a sex predilection for females over males reported as 4:1. Eighty percent of cases occur in children less than age 10 years old.

Etiology of CC remains unknown. The long common channel theory of Babbitt is the most widely accepted and postulates mixing of pancreatic and biliary juices, activation of pancreatic enzymes that cause resultant inflammation and deterioration of the biliary duct wall leading to dilatation. An alternate theory is congenital ductal obstruction with resultant dilatation of the common bile duct system. Complete cyst excision without compromising the pancreatic duct and common pancreaticobiliary channel should be performed as soon as the diagnosis is made to reduce the risk of malignancy later in life. Anomalous pancreaticobiliary junction is a risk factor for bile duct carcinoma and has junction location implications for operation.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Urgent surgery, either open laparotomy or laparoscopy, for rapidly enlarging CC, cholangitis, or worsening liver function profile. Sudden and severe narrowing of the terminal choledochus is more common in pediatric patients (76.2%) than adults (42.3%).

Early elective surgery, either open laparotomy or laparoscopy, for neonatal CC is advocated by most pediatric surgeons for prenatally diagnosed conditions even before the onset of symptoms. Rationale for early elective operation is risk reduction of surgical complications which become more common with older age at surgery.

2. Preoperative evaluation

The classic triad of symptoms of abdominal pain, jaundice, and palpable abdominal mass, is uncommon (6-20% of patients). Neonatal patients and infants generally present with obstruction; children with palpable abdominal masses; while older children and adults commonly present with abdominal pain.

Follow NPO guidelines for elective surgery.

3. What are the implications of co-existing disease on perioperative care?

Pancreatitis is the most common complication of CC and can present in up to 8% of pediatric patients. Ascending cholangitis may also be associated with CC.

c. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

Complications from ERCP may include hemorrhage, perforation, pancreatitis, and infection.

4. What are the patient's medications and how should they be managed in the perioperative period?

d. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Gabexate, a protease inhibitor, was found in a recent multicenter double blind study to prophylactically reduce pancreatic damage related to ERCP.

e. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia (MH)

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents. Follow a proposed general anesthetic plan: total intravenous anesthesia with propofol ± opioid infusion ± nitrous oxide. Ensure an MH cart is available [MH protocol].

Local anesthetics/muscle relaxants

Local anesthetics belong to two chemical classes (amides and esters). If a true allergy is present, it is most likely due to an ester class local anesthetic. Indeed, even in this rare situation the allergy may be from a local anesthetic metabolite such as para -amino-benzoic acid (PABA) or a preservative. If a true allergy is suspected, either a local anesthetic from another chemical class should be used or local anesthetic use should be withheld.

5. What laboratory tests should be obtained and has everything been reviewed?

Common laboratory normal values will be same for all procedures, with a difference by age and gender.

Abdominal ultrasound (US) is the initial imaging modality of choice which is noninvasive, inexpensive, and in most patients will lead to diagnosis of CC (71%-97% sensitivity). US allows precise measurement of diameter of common bile duct and degrees of intrahepatic dilation, degree of intrahepatic biliary dilatation, and presence of stones.

Cholangiography should then be performed to delineate biliary anatomy for operative planning. Magnetic resonance cholangopancreatography (MRCP) is the gold standard diagnostic imaging modality for visualization of the biliary tree, with high sensitivity (90%-100%) for diagnosis of CC. Benefits include noninvasive technique, avoidance of ionizing radiation, avoidance of general anesthesia, decreased risk of cholangitis or pancreatitis. Alternatively, ERCP may be done as diagnostic and therapeutic procedures via pediatric duodenoscopes. ERCP can provide information on the type of cyst, length of involved duct, presence and location of proetin plugs or calculi, pancreaticobiliary junction, and length of common channel required for preoperative planning. Drawbacks are necessity of general anesthesia and topical pharyngeal anesthesia in children older than 11 years old. The safety of ERCP without general anesthesia in infancy has not been fully documented.

CT scans may be useful showing continuity of the cyst with the biliary tree. HIDA scans are useful in the neonatal period to differentiate congenital CC from biliary atresia as the US images in both diseases are similar. Also useful for the diagnosis of CC rupture as will show entry of contrast into the peritoneal cavity.

Antenatal diagnosis can diagnose almost 15% of CC.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

General anesthesia with or without regional anesthesia is the mainstay of management for open surgery and robotic surgery for pediatric choledochal cyst. Premedication midazolam 0.5 mg/kg, maximum 10 mg. Inhalation induction with oxygen and sevoflurane or intravenous induction with propofol, neuromuscular blocker, intubation. An arterial catheter and a central venous catheter may be inserted. Maintenance anesthesia with oxygen, air, volatile agent of choice, and opioids. Avoid nitrous oxide to prevent bowel distension. If there is no coagulopathy, epidural catheter after induction or a regional nerve block for postoperative analgesia. Extubate in the OR.

a. Regional anesthesia

Neuraxial

High lumbar or low thoracic epidural anesthesia for postoperative pain management for open procedures usually in concert with general anesthesia. In infants and neonates, low thoracic epidural anesthesia usually by insertion of catheter by caudal canal after induction of anesthesia and intubation. In older children, epidural catheter may be placed at desired level after induction of general anesthesia.

Issues: Local anesthetics include 3% 2-chloroprocaine, 0.1-0.2% ropivacaine or 0.25% bupivacaine or levobupivacaine.

Peripheral nerve block

Paravertebral block (PVB). Local anesthetic infiltration of incision by surgeon may also be performed.

Benefits: PVB offers excellent intraoperative and postoperative analgesia, which reduce postoperative opioid requirements. Evidence supports PVB with the use of ultrasound as safe and efficacious in infant population.

Drawbacks: PVB have risks of intravascular injection, puncture of pleura, and bleeding.

Issues: Positioning issues (lateral with side to be blocked uppermost or prone) for PVB.

b. General Anesthesia

Benefits: Can be administered rapidly to secure the airway and facilitate complete control of airway, breathing and circulation. Titratable and easily reversible. Provides immobile patient, excellent amnesia, analgesia, and good muscle relaxation for long periods of operative time. Useful in patients with known allergy to local anesthetics.

Warming devices: fluid warmers, forced warm air blanket, humidification, and increase temperature in operating room. Give fentanyl early to eliminate pain that prevents breathing at the end of surgery.

What prophylactic antibiotics should be administered?

Prophylactic antibiotic received within one hour prior to surgical incision. First or second generation cephalosporins satisfy the criteria for most operations. If a patient is allergic to beta-lactams, fluoroquinolones and clindamycin in selected situations. Prophylactic antibiotics discontinued within 24 hours after surgery end time. Downloaded from SCIP (August 13, 2011) "CMS Core Measure SCIP Surgical Care Improvement Project." from http://www.sjhlex.org/documents/Physicians/SCIP_Poster_Full_Size.pdf.

What do I need to know about the surgical technique to optimize my anesthetic care?

Various types of drainage procedures such as RYHJ, hepaticoduodenostomy, jejunal interposition, hepaticoduodenostomy have been described, as well as laparoscopic excision of CC and hepaticoduodenostomy.

Discussion with surgeon as to surgical plan of either total cyst excision with hepaticoenterostomy by open or laparoscopic techniques of partial cyst excision with mucosectomy. Mucosectomy is good when inflammation and adhesions make complete cystectomy hazardous. Cyst excision and RYHJ via laparoscopy have quicker recovery (mean hospital stay 5.5 days), less adhesions, and improved cosmesis and ease of surgery. Robot assisted surgery for pediatric choledochal cyst has been described and validated in one retrospective study. Older patients with repeated cholangitis and marked pericystic inflammation may undergo resection anterolateral part of cyst and laparoscopic mucosectomy. Laparoscopic assisted and laparoscopic total cyst excision with the RYHJ has complication rates comparable to those of the open procedure.

What can I do intraoperatively to assist the surgeon and optimize patient care?

Supine, tilt to the right and head elevation of the operating table for lap procedure.

What are the most common intraoperative complications and how can they be avoided/treated?

CC can be associated with intraoperative complications such as bleeding, infection, obstruction and development of malignancy.

What level bed acuity is appropriate?

Step down or floor depending on the clinical condition of the patient.

What are common postoperative complications, and ways to prevent and treat them?

Operative mortality is 3%. Complications can be seen in 15% to 20% of patients. These include wound infection, anastomotic bile leak or stenosis, cholangitis, intrahepatic stones, septicemia, and bowel perforation. Complications are reduced in those children who present for earlier operation.

Early complications include anastomotic leak, pancreatic leak with injury to the pancreatic duct, bowel obstruction due to intussusception, and bowel kinking due to manipulation or adhesions. Late complications include peptic ulcer disease, cholangitis, biliary calculi, pancreatitis, liver failure and cancer. Fibrosis and inflammation of cyst tissue at the time of surgery such that the anastomosed margins are friable, result in poor healing, leakage, and anastomotic stricture.

Cirrhosis is rare when bile flow is re-established. Recurrent pancreatitis can manifest years after original CC has been removed.

(Authors evaluate robotic surgery for pediatric choledochal cyst versus open surgery in a small retrospective study, and their findings support the validity and feasibility of robotic surgical techniques in pediatric choledochal cyst.)